Electrical apparatus adapted to operate at very high frequencies



June 5, 1945. D. c. ESPLEY EI'AL 2,377,680

ELECTRICAL APPARATUS ADAPTED TO OPERATE AT VERY HIGH FREQUENCIES FiledJan. 2, 1942 FIG. 1.

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Patented June 5, 1945 ELECTRICAL APPARATUS .ALDAPTED To l OPERATEATVEBYHIG HT REQUENCI ES Dennis Clark Espley, North Wembley, and John .WalterRyde London WL14,England, assignors i l p g. touThe General. ElectricCompany Limited, l a a London W. 0.2, England ApplicationJanuary 2,1942, Serial No. 425,430 v In Great Britain November'4,1940g a 1 23Claims. (c aste-3e).

This invention relatesto electrical apparatus adapted to operate athighirequencies (an-d more especially" at frequencies corresponding. towave- ,length invacuo of less than 1 metre) ofthe type comprising a pairof conductors arranged side by side and cooperating to form atransmission line along which there are standing electric waves. Theconductors may be, for example, apair of parallel rods or a pair ofconcentric cylinders.

In such apparatus oscillating Voltages maybe developed betweencorrespondingpoints on the conductors that'a're very muchhigher than anysteady voltage applied to the apparatus; the power of the oscillationsthat can be generated in the apparatus may then be limited by thepassage open atfone endand oupled at a given point spaced-from thesaidjIoneend. to a wave-signal translating apparatus to develop along theline standing waves of potential having a maximum value limited pby thecorona dischargebetween X the conductors at theaforesaid open end; The

of a discharge through the air between the conductors or by theformation of a}corona on one or both of them. The object of thisinventionis to l l increase the limit set to the powerby this possibility. a 1 A It is well known that a discharge from or a corona on aconductor can be suppressed by surrounding the conductor with adielectric of a-dielectric strengthand dielectric'constant greater thanthat of air. Solid and liquid dielectricsof high dielectric strength areundesirable in apparatusof thetyp'e specified because the dielectricloss .inthem is too great. The other alternatives are a vacuum or a gasat a pressure higher than atmospheric. But theme of these dielectricsrequires the presence of a sealed envelope around the conductor;theproblem then arises of making connection "between the conductorinside theenvelope andythe rest of the apparatus outside withoutincurring the danger of a discharge .orfcorona. This problem can besolved by arranging matterstso that the connecting partis at or near avoltage node of the oscillations, so that the part is exposed only tosmall oscillating voltages. According to the invention a high-frequencyelectric oscillation generator comprises a pair ofthermionicvalvesatleast two of the leads to which co-1operate to form atransmission line along which there are standing electric waves andwherein at least one of the leadsis enclosed throughout the greater partof its length in a sealed envelope, the pointswhere any part of the onelead emerges from theenvelope for connection toa part of the associatedone ofithe valves, that is not grounded for high-frequency oscillations,being in the neighborhood of a voltagenode of'the oscillations. l F g.In accordancewith a particular formof the invention, a high-frequencywave-signal translating system comprises a pair of conductorscoopsystem;includes a non-conductive sealed envelope enclosingthe open end ofatleast oneof the'conductors ina medium at such pressure assubstantially to increase the maximum potential at which the coronadischarge is initiat'edbetween the conductors at the open end oftheline, the envelope terminating at one end alongthe aforesaid oneconductor substantially only in the neighborhood therealong. t

If there is of avoltage node of the standingwave developed a high vacuumwithin the envelope there will be little difiiculty in securingthe'necessary. dielectric strength. But sincesome power is alwaysdissipated in the conductors, it maybe difficult to cool them sufficiently. Then the sealed envelope may containcompressed gas. Carbondioxide is a convenientgas; for; in orderto avoid thedifiicultyjofsealing ch 9, vesselcontaining gas {at high pressure,thegas may becondensedby cold duringthesealing off. (No novelty claimedfor this deviceperse.) Alternatively, vapours,

such asthose of carbon tetrachloride, or dichlorodifiuoro-methane, whichare known to have great dielectri f trength, maybe used in place ofcarbon dioxide. i l

Apparatus of the type specified is often operated at high altitudeswhere the atmospheric pressure is muchless than normal. It may happenthen that acorona orldischarge occurs only when the apparatus is takento such altitudes. Then the sealed envelope maybe filled with air atnormal atmospheric pressure; for in the circumstancesof use the gas willbe compressed, i. e.,

at a pressure higher than that oi the surroundingregion.

Two embodiments of theinvention will now be described by Way of examplewith reference to theaccompanying drawing,inwhich Figure 1 is asectional diagram of part of a high frequency electric oscillationgenerator;

erating to provide a resonanttransmissionline 1 Figure 2 is a diagram ofthe samegenerator, 'drawn toa smaller scale, and showing elements notappearingin Figure 1; and i l Figure 3 is a sectional diagram of tiveembodiment.

an alterna- In Figs. 1 and 2 a pair of thermionic valves I, l, arrangedto operate in push-pull, have external anodes 2, 2'. The anodeareeffectively continuous with the copp r discs, 3, 3', into holes whichthey are set. 4, 4' arevthe cathode con nections emerging at one end ofeach valve; as shown in Figure 2, these connect to lines I4, I4, eachconsisting of a pair of concentric conductors insulated from oneanother. One end of the cathode heating element of Valve I is connectedto the inner conductor of the line I4, while the other end of theheating element and the oathode emitting surface are connected in commonto the outer conductor of line I4. The heating element and cathode ofvalve I' are similarly connected to the conductor of line M. The linesI4, l4 form a parallel transmission line terminated by an adjustabletuning bridge I5. The cathode heater battery is denoted by I6. 5, 5 areterminals to the control grid emerging at the other end of each valve.

The said pair of conductors, being straight A parallel rods, which areattached at one end to the grid terminals 5, 5', include straightparallel rods 6, 6'. Standing waves are set up along these conductorsand the length of the conductors is so adjusted relative to thewave-length of the oscillations thatthe ends joined to 5, 5' are at ornear a voltage node. Each rod 6, 6' is enclosed within a sealed glassenvelope I, 'I' filled with carbon dioxide to a pressure of 2atmospheres or more. i I

Inorder that 6, 6' may be connected to 5, 5, the terminal 5 or 5' is athreaded plug projecting from the bottom of a metal thimble 8, 8 sealedat its edge to the glass 9, 9' of the valve. (This construction is knownper se.) The end of 6, 6 is a similar plug l0, l brought out similarlyfrom the end of the envelope 1, I. II, II are metal connecting pieces,having a threaded hole at each end intov which the plugs 5, and

crating to provide a resonant transmission line open at one end andcoupled at a given point spaced from said one end to a wave-signaltrans- Ill, I0 are screwed. Exact tuning can be efiected by adjustingthe lengths of the pieces I I, I I.

All the parts mentioned are mounted on the metal plate I2, provided withducts l3 through which a coolant is circulated.

The plate I2 is grounded for high-frequency oscillations and isconnected through a battery I'I, supplying the anode current for thevalves, to each of the cathode lines I4, l4. Conventional grid-leakresistors I8, I8 are connected in series between the connecting piecesII, II, and the junction of the resistors is connected to one terminalof the battery I6. The grids of the valves I, l' are thus operated aboveground for both high-frequency and unidirectional-bias potentials.

The open-ended transmission line formed by the conductor rods 6, 6', theconnecting pieces II, II, and the grid leads within the envelopes of thevalves I, I thus has an elctrical length M2, where A denotes the wavelength'of the standing waves in the line; and the part of this lineconstituted by the enclosed conductor rods 6, 6' has an .electricallength substantially M4.

InFigure 3, a thermionic valve I, constructed and mounted similarly toeach of the valves I, I in Figure 1, is associated with a pair ofconcentric cylindrical conductors 6A and 6B. The inner cylindricalconductor 6A, which is attached by the connecting piece II to the gridterminal 5 of the valve, is enclosed within the sealed glass envelope I,which may be evacuated or charged with any of the gases or vapourshereinbeiore specified. The outer cylindrical conductor 6B, which is notenclosed in an envelope, is mounted on th metal plate I2.

What We claim as new is:

1. A high-frequency wave-signal translating system comprising, a pair ofconductors co-oplating apparatus to develop along said line standingwaves of potential having a maximum value limited by the coronadischarge between said conductors at said open end, and a nonconductivesealed envelope enclosing the open end of at least one of saidconductors in a medium at such pres.- sure as substantially to increasethe maximum potential at which a corona discharge is initiated betweensaid conductors at said open end of said line, said envelope terminatingat one end .along said one conductor substantially only in theneighborhood of a potential node of the standing wave developedtherealong.

2. A high-frequency wave-signal translating system comprising, a pair ofparallel conductors co-operating to provide a resonant transmission lineopen at one end and coupled at a given point spaced from said one end toa wave-signal translating apparatus to develop along said line standingwaves of potential having a maximum value limited by the coronadischarge between said conductors at said open end, and a pair ofnonconductive sealed envelopes enclosing the open ends of individualones of said conductors in a medium at such pressure as substantiallytoincrease the maximum potential at which a corona discharge is initiatedbetween said conductors at said open end of saidline, each of saidenvelopes terminating at one end along the conductor enclosed therebysubstantially only in the neighborhood of a potential node of thestanding Wave developed therealong.

3. A high-frequency wave-signal translating system. comprising, a pairof concentric cylindrical conductors co-operating to provide a resonantcoaxial transmission line open at oneend and coupled at a given pointspaced from'said one end to a wave-signal translating, apparatus to develop along said line standing waves of potential having a maximum valuelimited by the corona discharge between said conductors at said openend, and a nonconductive sealed envelope enclosing the open end of theinner one of said conductors in a medium at such pressure assubstantially to increase the maximum potential at which a coronadischarge is initiated between said conductors atsaid open end of saidline, said envelope terminating at one end along said inner,

conductor substantially only in the-neighborhood of a potential node ofthe standing wave developed therealong.

4. A high-frequency wave-signal translating system comprising, apair ofconductors co-operating to provide a resonant transmission line open atone end and coupled at a given point spaced from said one end to awave-signal translating apparatus to develop along said line standingwaves of potential having a maximum value limited by the coronadischarge between said conductors at said open end, and a nonconductiveevacuated envelope enclosing the open end of at lease one of saidconductors substantially to increasethe maximum potential at which acorona discharge is initiated between said conductors at said open endof said line, said envelope terminating at one end along said oneconductor substantially onlyin th neighborhood of a potential node ofthe standing wave developed therealong. 5. A high-frequency wave-signaltranslating system comprising, a pair of parallel conductorsco-operating to provide a resonant transmission line open at one end andcoupled at a given point lating apparatusto:developalone said linestande ing waves of potentialhaving amaximu'm value limited bythe:corona discharge between said conductors atsaid open end, and apair ofnon conductive evacuated envelopes? enclosing the open ends ofindividual ones of said conductors substantially to increase the maximumpotential A 2,377,680 spacedfrom said'one endto awave-signaltrans- 1 toa wavewsignal translating apparatus :to de- A velop along said linestanding wavesof potential having a maximum value limited by the coronaat which a corona discharge is initiated between said conductors at saidopen end of said line, each inl'the neighborhood of apotential node ofthe standing; wave developed therealong.

A a high-frequency wave-signal translating system comprising, a pair ofconcentric cylindrical conductors co-operating to provide airesonantcoaxial transmission line open at one end and coupled at a given pointspaced from said one end to a wave-signal translating apparatus todevelop along said line standingwaves of potential having a maximumvalue limited by the corona discharge betweensaiduconductors at saidopen end, and a nonconductive evacuated envelopeenclosing the open endof theinner oneof said conductors substantially to increase the maximumpotential at which a corona discharge is initiated between saidconductors at said open end of said line, said envelope terminating atone end along said inner conductor substantially only in theneighborhood of a potential node o fthe standing wave developedtherealong.

discharge between said conductors at said open end, and a nonconductivesealedenvelope enclospotential atwhich a corona discharge isjinitiatedbetween said conductors at saidopen end of said line, said envelopeterminating at one end along ,said inner conductorlsubstantially only inthe 7. A high-frequency wave-signal translating system comprising,ap'airrof conductors co-operating' to provide a resonant transmissionline open at one endand coupled at a given point spaced from said oneendto a wave-signal translating apparatus to develop along said linestanding wavesof potential having a maximum value limited by the coronadischarge between said con- (meters at said open end, and anonconductive sealed :envelope'enclosing the open end of at least one ofsaid conductors in awgaseous medium at superatmospheric pressuresubstantially to in crease the maximum potential at which a coronadischarge is initiated between saidconductors at said; open end ofsaidlineysaid envelope terminating at one end along said one conductorsubstantially only in the neighborhood of a potential node of thestanding wave developed therealong.

i8.A high-frequency wave-signal; translating system comprising, a pairof parallel rod conductors co-operating toprovide a resonanttransmission line open at one end and coupled at a'given point spacedfrom said one endyto a wave-signal translating apparatus to developalong said'line standing Waves of potential having a maximumvaluelimited by the corona? discharge between said conductors at saidopen end, and a pair of nonconductivesealed envelopes enclosingthe openendsof individual ones of said conductorsin a gaseous medium atsuperatmosphericpressure standing wave developed therealong.

9. A high-frequency wave-signal translating system comprising, a pair ofconcentric cylindrical conductors co-operating to provide a resonantcoaxial transmission line open at one and coupled at a givenpoint spacedfrom said one end neighborhood of a potential node of the standingwavedeveloped therealong. A

10. A high-frequency wave-signal translating system comprisinga pair ofconductors co-operating toprovide a resonant transmissionline open atone end and coupled at a given point spaced from said one end to atwave-signaltranslating apparatus to develop along said line standingwaves of potential having a maximum value limited by the coronadischarge between said conductors at said open end, and a nonconductivewhich a corona discharge is initiated between said conductors at saidopen end of said line, saidenvelope terminating at one end along saidone conductor substantially onlylin the neighborhood of a potential nodeof the standing wave developed therealong.

1 A ll. A high-frequency wave-signal translating system comprising, apair of conductors co-operatingtoprovide a resonant transmission line'open 7 atom end and coupledat a given pointspaced from said one end toa wave-signal translating apparatus to develop along said line standingwaves of potentialhavinga maximum value limited bythe corona dischargebetweensaid conductors at said openenol, and a nonconductive sealedenvelope. enclosing the open end of at'least A A one of said'conductorsin the vapour of ama terial having great'dielectric strength andat suchpressure as substantially to increase the maximum potential at which'acorona discharge is initiated between said conductors at said open endof said line, said envelope terminating at one end along said oneconductor substantially only in the neighborhood of a potential node ofthe standing wave developed therealon'g. J it 3 12. A high-frequencywave-sign'al'translating system comprising, a pair of conductors co-operating toprovide a resonant transmission line open at one end andcoupledat a given point spaced from said one end to a wave-signaltranslating apparatus to develop along said line standing waves ofpotential having a maximum value limited by the corona discharge betweensaid con ductors at saidopen end, and a nonconductive sealed envelopeenclosingthe open end of at least one of said conductors incarbon-tetrachloride vapour at such pressure as substantially toincrease the maximum potential at which a corona discharge is initiatedbetween said conductors: atsaid open end of said line, said envelopeterminating at one end along said one conductor substantially only'inthe neighborhood of a potential node of the standing wave developedtherealong.

13. A high-frequency wave-signal translating 1 system adapted to be usedat high altitudes comprising, a pair of conductors co-operating toprovide a resonant transmission line open atoneend and coupled at agiven point spacedfrom said one end to-a wave-signal translatingaptions.

paratus to develop along said line standing waves ofp'otential having amaximum value limited by the corona discharge between said conductors atsaid open end, and a nonconductive sealed envelope enclosing the openend of at least one of said conductor in air at normal atmosphericpressure substantially to increase the maximum potential at which acorona discharge is initiated between said conductors at said open endof said line when said system is operated at said high altitudes, saidenvelope terminating at one end along said one conductor substantiallyonly in the neighborhood of a potential node of the standing wavedeveloped therealong.

- '14; A highfrequency electric oscillation generator comprising a pairof thermionic valves at least two" of the leads to which co-operate tofor'ma transmission line along which there are standing electric wavesand wherein at least one said lead is enclosed throughout the greaterpart of its length in a sealed envelope, the points Where any part ofsaid one lead emerges from said envelope for connection to a part of theassociated one of said valves; that is not'groundecl for high frequencyoscillations, being in the neighborhood of a voltage node of theoscilla- 115.-A high frequency electric oscillation generator comprisinga pair of thermionic'triodes operating in push-pull and whose grid leadsare parallel rods which co-operate to form a transmission line alongwhich there are standing electric waves, wherein each said grid lead isenclosed throughout the greater part of its length in a sealed.venvelope containing carbon dioxide at superatmospheric pressure and thewhole of the part of each said grid lead lying between said sealedenvelope and the envelope of the corresponding thermionic valve is inthe neighborhood ,of a voltage node of the oscillations.

17. A high frequency electric oscillation generator comprising a pair ofthermionic triodes operating in push-pull and whose grid leads areparallel rods which co-operate to form a transmission line along whichthere are standing electric waves, wherein each said grid lead isenclosed throughout the greater part of its length in a sealed envelopecontaining the vapour'of a material having great dielectric strengthandthe Whole of the part of each said grid lead lying between said sealedenvelope and the envelope of the corresponding thermionic valve is inthe neighbourhood of a voltage node of the oscillations.

18. A high frequency electric oscillation generator'comprising a air ofthermionic triodes operating in push-pull and whose grid leads are highdielectric strength. I

21.. A high frequency electric oscillation genparallel rods whichco-operate to form an openended transmission line of electricallength-M2 along which there are standing electrical waves of wavelengthX and wherein each said grid lead is enclosed throughout a lengthofsubstantially M4 from the open end of said line in a sealed envelope. I

19. A high frequency electric oscillation generator comprising a pair ofthermionic triodes operating in push-pull and whose grid leads'areparallel rods which 'co-operate-to form an openended transmission lineof electrical length M2 along which there are standing electrical wavesof wavelength A and wherein each said grid lead is enclosed throughout alength'of substantially M4 from the'open end of said line ina sealedenvelope containing carbon dioxide at 'superatmospheric pressure. i

20. A high frequency electric oscillation generator comprising a pair ofthermionic triodes operating in push-pull and whose grid leads areparallel rods which co-operate' to form an openended transmission line'of electrical length M2 along which there are standing electrical Wavesof wavelength A and wherein each said grid lead is enclosed throughouta'length of substantially M4 from the o'penend of said line in a sealedenvelope containing the vapour of a material of eratorcomprising a pairof'thermio'nic triodes operating in push-pull and whose gridleads areparallel rods. Which-co-operate toform a transand the envelopeof thecorresponding thermionic valve is in the neighbourhood of a voltage nodeof the oscillations and wherein the cathode leads of said valves form aparallel line terminated by an adjustable bridge for tuning.

22. A high frequency electric oscillation generator comprising a pair ofthermionic triodes operating in push-pull and whose grid leads areparallelrods which co-operate to form an openendedtransmission line ofelectrical length'M2 along which there are standing electrical waves ofwavelength x, wherein each said grid lead is enclosed Ithroughoutalength of substantially M4 from the open-end of said linein a sealedenvelope'and wherein the cathode leads of said valves form a parallelline terminatedby an adjustable bridge fortuning.

23. A high frequency electric, oscillation generator comprising a pairof thermionic triodes operating in push-pull and whose grid leads areparallel rods which co-operate to form an openended transmission line ofelectrical length M2 along which there are standing electrical waves ofwavelength x, wherein each said grid lead is enclosed throughout alength of substantially M4 from the open end of said line in a sealedenvelope containing carbon dioxide at superatmospheric pressure andwherein the cathode leads of said valves form a parallel line terminatedby an adjustable bridge for tuning. 7/

DENNIS CLARK ESPLEY.

JOHN WALTER RYDE.

